This invention relates to a new organophosphorus compound and particularly, to phosphorus-containing condensation products and process for the production thereof.
Organophosphorus compounds have been used as a flame retardant for various synthetic resins as disclosed in, for example, U.S. Pat. Nos. 3,247,134, 3,262,894, 3,278,464 and 3,368,916. However, when the conventional organophosphorus compounds are added in an amount sufficient to impart flame retardancy, they have a disadvantage of lowering the thermal deformation or degradation temperature of synthetic resins.